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A319 Ailerons Drooping

Mon Sep 06, 2004 7:00 pm

today i noticed that on one of our A319s both ailerons were drooping down. how can that be with fly-by-wire controls?
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RE: A319 Ailerons Drooping

Mon Sep 06, 2004 8:40 pm

Easy: No hyd pressure plus the weight of the aileron Equals droop. "Fly by wire" only means control by wire ( electrically ) via computers. Hydraulics still do the "heavy lifting".
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RE: A319 Ailerons Drooping

Mon Sep 06, 2004 10:50 pm

Noticed that Airbuses' flight controls droop pretty easily... I mean almost all kinds of their planes have the ailerons droop or 'drop' when the hydraulics are turned off but I don't seem to notice the same trend on many Boeings. Especially for the B744s, which the control surfaces are supposedly heavier but they don't seem to droop, not even the high speed ailerons... same goes for the B767.. or so. But the B777s do have the control surfaces droop pretty easily. Is this due to the different systems that power the controls? Seem to notice that FBW can droop easier...

Any explanation?

When I read this all over it sounds so odd Big grin
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RE: A319 Ailerons Drooping

Mon Sep 06, 2004 10:57 pm

Not really right on topic, but I have also noticed that some a/c, especially the A32x family, have their rudders blown by the wind to either side.

Don't those a/c have some kind of gust lock device?
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RE: A319 Ailerons Drooping

Mon Sep 06, 2004 11:24 pm

The construction of the actual hinge and mechanism probably differs slightly from plane to plane, which would explain the differences in behavior. I don't know exactly how they are built, but a simple counterweight in the mechanism would eliminate drooping, for example.
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RE: A319 Ailerons Drooping

Tue Sep 07, 2004 12:33 am

"Not really right on topic, but I have also noticed that some a/c, especially the A32x family, have their rudders blown by the wind to either side."

If you go to DFW terminal A, when there is the usual strong breeze from the south, all of AA's 777's will have their rudders looking like they are making a hard turn to the right.

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RE: A319 Ailerons Drooping

Tue Sep 07, 2004 12:45 am

If on takeoff/landing, the Airbus FBW software is programmed to droop the ailerons when full flap is selected.
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RE: A319 Ailerons Drooping

Tue Sep 07, 2004 1:36 am

What's with all the drooping aileron questions lately?  Smile

A320 series ailerons and elevators droop because pressure is not retained in the servos when hydraulics are off. There is nothing special about fly by wire that would cause it, other than the lack of cables.

Rudders on all large aircraft will displace in a strong wind. Large aircraft don't have gust locks on the rudder (not even the Dash-8), they have dampers, that protect the rudder from being slammed over.

Incidently, the newest A320 series ailerons don't droop. Not sure what's different about them, I'll see what I can find out.
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RE: A319 Ailerons Drooping

Wed Sep 08, 2004 8:12 am

You'll find that Boeing's have the aileron droop on the groun too. The 767's maily just the inboards and the elevators.

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